package org.ielse.frame.t.view.markushi.util;

import android.view.animation.Interpolator;

/**
 * A pre-baked bezier-curved interpolator for indeterminate progress animations.
 */
public final class BakedBezierInterpolator implements Interpolator {
	private static final BakedBezierInterpolator INSTANCE = new BakedBezierInterpolator();

	public final static BakedBezierInterpolator getInstance() {
		return INSTANCE;
	}

	/**
	 * Use getInstance instead of instantiating.
	 */
	public BakedBezierInterpolator() {
		super();
	}

	/**
	 * Lookup table values. Generated using a Bezier curve from (0,0) to (1,1)
	 * with control points: P0 (0,0) P1 (0.4, 0) P2 (0.2, 1.0) P3 (1.0, 1.0)
	 * 
	 * Values sampled with x at regular intervals between 0 and 1.
	 */
	private static final float[] VALUES = new float[] { 0.0f, 0.0002f, 0.0009f, 0.0019f, 0.0036f, 0.0059f, 0.0086f, 0.0119f, 0.0157f,
			0.0209f, 0.0257f, 0.0321f, 0.0392f, 0.0469f, 0.0566f, 0.0656f, 0.0768f, 0.0887f, 0.1033f, 0.1186f, 0.1349f, 0.1519f, 0.1696f,
			0.1928f, 0.2121f, 0.237f, 0.2627f, 0.2892f, 0.3109f, 0.3386f, 0.3667f, 0.3952f, 0.4241f, 0.4474f, 0.4766f, 0.5f, 0.5234f,
			0.5468f, 0.5701f, 0.5933f, 0.6134f, 0.6333f, 0.6531f, 0.6698f, 0.6891f, 0.7054f, 0.7214f, 0.7346f, 0.7502f, 0.763f, 0.7756f,
			0.7879f, 0.8f, 0.8107f, 0.8212f, 0.8326f, 0.8415f, 0.8503f, 0.8588f, 0.8672f, 0.8754f, 0.8833f, 0.8911f, 0.8977f, 0.9041f,
			0.9113f, 0.9165f, 0.9232f, 0.9281f, 0.9328f, 0.9382f, 0.9434f, 0.9476f, 0.9518f, 0.9557f, 0.9596f, 0.9632f, 0.9662f, 0.9695f,
			0.9722f, 0.9753f, 0.9777f, 0.9805f, 0.9826f, 0.9847f, 0.9866f, 0.9884f, 0.9901f, 0.9917f, 0.9931f, 0.9944f, 0.9955f, 0.9964f,
			0.9973f, 0.9981f, 0.9986f, 0.9992f, 0.9995f, 0.9998f, 1.0f, 1.0f };

	private static final float STEP_SIZE = 1.0f / (VALUES.length - 1);

	@Override public float getInterpolation(float input) {
		if (input >= 1.0f) {
			return 1.0f;
		}

		if (input <= 0f) {
			return 0f;
		}

		int position = Math.min((int) (input * (VALUES.length - 1)), VALUES.length - 2);

		float quantized = position * STEP_SIZE;
		float difference = input - quantized;
		float weight = difference / STEP_SIZE;

		return VALUES[position] + weight * (VALUES[position + 1] - VALUES[position]);
	}

}